Direct measurement of the hydrogen-bonding effect on the intrinsic redox potentials of [4Fe-4S] cubane complexes.
Direct measurement of the hydrogen-bonding effect on the intrinsic redox potentials of [4Fe-4S] cubane complexes.
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DOI：
10.1021/ja045709a
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发表时间：
2004-11
影响因子：
15
通讯作者：
Xin Yang;S. Niu;T. Ichiye;Lai‐Sheng Wang
中科院分区：
文献类型：
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作者：
Xin Yang;S. Niu;T. Ichiye;Lai‐Sheng Wang
为了探究氢键如何影响 Fe-S 蛋白中的氧化还原电位变化，我们制备并研究了一系列气态立方烷型类似物配合物 [Fe(4)S(4)(SEt)(3)(SC(n)H(2n+1))](2-) 和 [Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](2-) (n = 4, 6, 11； Et = C(2)H(5))。通过光电子能谱测量了这些配合物中涉及的[Fe(4)S(4)](2+/3+)氧化还原对的固有氧化还原电位。从[Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](2-)到[Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](-)的氧化能直接从光电子能谱测定，比相应的氧化能高约130 meV [Fe(4)S(4)(SEt)(3)(SC(n)H(2n+1))](2-)体系，因为前者中有OH...S氢键。初步蒙特卡罗和密度泛函计算表明，氢键发生在[Fe(4)S(4)(SEt)(3)(SC(6)H(12)OH)](2-)中末端配体上的-OH基团和S之间。目前的数据提供了净氢键对[Fe(4)S(4)]簇氧化还原电位影响的直接实验测量，而不受其他环境影响的干扰。
To probe how H-bonding effects the redox potential changes in Fe-S proteins, we produced and studied a series of gaseous cubane-type analogue complexes, [Fe(4)S(4)(SEt)(3)(SC(n)H(2n+1))](2-) and [Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](2-) (n = 4, 6, 11; Et = C(2)H(5)). Intrinsic redox potentials for the [Fe(4)S(4)](2+/3+) redox couple involved in these complexes were measured by photoelectron spectroscopy. The oxidation energies from [Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](2-) to [Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](-) were determined directly from the photoelectron spectra to be approximately 130 meV higher than those for the corresponding [Fe(4)S(4)(SEt)(3)(SC(n)H(2n+1))](2-) systems, because of the OH...S hydrogen bond in the former. Preliminary Monte Carlo and density functional calculations showed that the H-bonding takes place between the -OH group and the S on the terminal ligand in [Fe(4)S(4)(SEt)(3)(SC(6)H(12)OH)](2-). The current data provide a direct experimental measure of a net H-bonding effect on the redox potential of [Fe(4)S(4)] clusters without the perturbation of other environmental effects.